1. Field of the Invention
The present invention relates to a method for the allocation of passengers in an elevator group comprising multi-door elevators.
2. Discussion of the Background
Prior art is described in Finnish patent application FI-A-20000502 (B66B 1/18), which discloses a solution relating to the allocation of passengers to the elevators in an elevator bank. In this passenger allocation solution, each passenger gives his/her destination floor. The starting floor being known on the basis of the location of the call input device, it is possible to obtain unambiguous information regarding passengers trying to get onto the system. With these initial data, the elevator group control is able to find a preferable elevator for each passenger. This is called passenger allocation.
In this solution, the decision making is based on e.g. genetic algorithms. First, a number of alternative solutions, i.e. chromosomes are created, the quality of which as allocation decisions is determined. After this, the set of alternative solutions is subjected to refinement by genetic methods, which include the selection of representative solution alternatives for the next generation and as parents for descendants, the generation of descendants, i.e. new solution alternatives, by crossbreeding the best solution alternatives of each instant with each other and/or by applying changes or mutations to the genes of the descendants created. A quality factor has to be determined for each descendant, whereupon the next generation of solution alternatives can be created or, if a termination criterion is fulfilled, the best alternative in the set of solutions is selected as the solution to the problem. Without a genetic algorithm, the best solution is found by a heuristic method e.g. by finding a routing alternative that minimizes the call time and using a prior-art technique, which is described in US patent specification 5616896 (B66B 1/42).
In genetic passenger allocation, the subject considered is expressly the passengers, in other words, a decision is made as to which elevator car is to serve each passenger. Each passenger gives his/her destination floor using a call input device on the starting floor, and thus the data for each passenger is known in the elevator system. The elevator system also has to inform each passenger as to which elevator is going to serve him/her. Once the passenger has been thus informed, it is no longer possible to change the elevator car offered to him/her.
US patent specification 5689094 (B66B 1/20) again discloses an elevator group comprising passenger terminals located on each floor. In the elevator group described in this specification, destination calls can be entered from the aforesaid passenger terminals via input means, which may consist of e.g. a keyboard. Information regarding allocated elevators is presented to the user on a display device placed at the aforesaid passenger terminal immediately after a destination call has been given. A second display is provided above the landing door to tell the passenger which elevator car will serve the desired floor.
A problem with the prior-art solutions is that a given elevator car is always definitively assigned to serve a given call entered by a passenger in the elevator group. Therefore, the elevator control system can not later change the elevator assigned to a given call. On the other hand, in the case of a multi-car elevator group comprising several lobbies, it does not make any great difference to the passenger which elevator car is going to serve him/her. In addition, it may be difficult for the passenger to distinguish the elevator car assigned to a given call.
Also, the problems related to immediate allocation of calls in the traditional up/down button group control are not directly comparable with the problems of immediate allocation in the case of destination allocation, which is due to the fact that, in destination allocation, information regarding the destination of an individual passenger is obtained immediately in connection with the hall call and the passenger can not influence the formation of the route of his/her elevator trip.